For example, in a manufacturing of a semiconductor device, e.g., an etching process or a film forming process is performed by using a plasma.
A plasma processing using the plasma, is usually performed by a plasma processing apparatus installed in a clean room. A parallel plate type plasma processing apparatus including an upper and a lower electrode is widely used. The plasma processing apparatus includes, for example, in a processing vessel, the upper electrode to which a high frequency power for generating the plasma is applied, a lower electrode on which a substrate is mounted, and the like. And, by reducing a pressure in the processing vessel to a predetermined pressure, supplying a processing gas into the processing vessel, and then applying the high frequency power for generating the plasma to the upper electrode, the plasma is generated in the processing vessel, and is employed to etch a film on the substrate.
The plasma processing is performed under a high temperature condition to generate the plasma. However, it required to maintain a temperature in the processing vessel or a substrate temperature at a constant value in order to make a processing state of the substrate stable. On this account, a chiller unit for circulating and supplying a coolant is normally connected to, for example, the lower electrode or the upper electrode of the plasma processing apparatus to remove an accumulated heat in the electrode.
In general, the chiller unit is installed under a floor of the clean room in which the plasma processing apparatus is installed. The electrode is cooled by supplying a coolant thereto through a circulation path extending from the chiller unit to the plasma processing apparatus (see, for example, Japanese Patent Laid-open Application No. 2001-332463). Further, the chiller unit is separately installed for each electrode because a control temperature of the upper electrode is different from that of the lower electrode.
However, in case a distance from the plasma processing apparatus to the chiller unit is long as usual, a coolant storage tank is required in the chiller unit to supply the coolant to the electrode after a coolant temperature is stabilized. This makes a size of the chiller unit large. Further, the large-sized chiller unit is individually installed for each of the upper and the lower electrode, and thus, a large space is required for installing the separate chiller units. In recent, it is also required to control temperatures of members other than the upper and the lower electrode to control the processing state of the substrate more strictly. Therefore, a larger space is further required in case of installing the chiller unit for each of the members.
Besides, because there is a need to store the coolant in the storage tank, the amount of the coolant used is increased accordingly, and thereby a cost of the coolant is increased.